First - what is the actual lameness - is it laminitis (caused by over-feeding), or is it scald/footrot (caused by wet bedding/damp field) or something else entirely?
If scald/footrot - treat in the same way as you would sheep, and I have found the best way (for my sheep) is to foot-bath with a product called "Lameless" combined with an antibiotic injection (Alamycin LA).
I personally don't know anything really about laminitis - but gooogle Laminitis in goats and it should give you some ideas.
A vet can prescribe ANY medication licensed for ANY animal if s/he thinks it is of benefit, however they may make you sign a waiver in case of unforeseen problems. It's called the cascade system, and due to the low number of medicines licensed for goats we have to "borrow" a lot from either sheep or cattle... dose rates may be different though. If you don't milk her (and I presume you are not planning on eating him/her) then you shouldn't have any issues with withdrawal times...